its the file's executable permission you want to modify, not the home directory -
"chmod 755 hlds_run"
should work - you may have to be root if root owns the file.
also, are you issuing that entire line as a command? the "./" tells the shell to look in the present directory for the executable - so if you cd to /home/cs1/hlds first, run
if you are not in that dir, then you'd run
but not both at the same time